WEST LAFAYETTE, Ind. — Prosecutors filed a murder charge Thursday against a Purdue University student accused of killing a fellow teaching assistant in a shooting that had the entire campus on lockdown.

In his first court appearance, Cody Cousins, 23, of the Dayton suburb of Centerville, Ohio, was told the prison sentence for such a charge is 45 to 65 years plus a possible $10,000 fine, but any aggravated circumstances — which had not been filed as of late Thursday afternoon — could raise the stakes to life in prison or the death penalty.

He was denied bond, a standard practice in a murder case, and will continue to be held in the Tippecanoe County Jail.

Cousins is accused of killing Andrew Boldt, 21, of the Milwaukee suburb of West Bend, Wis., at about noon Tuesday in the basement of the Electrical Engineering Building, where both served as undergraduate teaching assistants. After the campus was alerted, students at the school of 30,000 students 60 miles northwest of Indianapolis spent more than an hour sheltering in place.

As police arrived on the scene shortly after the shooting, an officer saw Cousins sitting on the ground outside the building with his hands behind his head as others fled, according to a probable cause affidavit filed along with the charge. Upon further inspection, the officer saw blood on Cousins' hands and clothes. He then was taken into custody.

Other officers who entered the building saw bloody footprints near the room where the shooting occurred, court documents show. Inside the classroom, police discovered Boldt's body, which had been shot and stabbed.

They recovered a handgun, knife and several spent shell casings near Boldt's body. Witnesses in the room reported they saw Cousins stab and shoot Boldt; surveillance footage also showed Cousins in the building, the affidavit said.

Information on the number of shots fired was not included in court documents.

During Thursday's hearing, Cousins spoke only to answer questions from Magistrate Sean Persin of Tippecanoe County Superior Court indicating that he understood the charges and possible sentence. Persin entered a not guilty plea for Cousins.

Also in the courtroom were Cousins' mother, Wendy Melancon; father, Ernest Cousins; and sister; they did not speak. Persin set a preliminary trial date for April 22.

Outside the courtroom, some have described Cody Cousins as easy going, but others have said he is rude and sometimes disagreeable.

"I recall that he was an intensely serious student by his demeanor," Clark said. "He did not mingle much with others and he rarely asked questions."

Clark said Cody Cousins did not come to his office hours so he had little one-on-one interaction with him. The student did attend Clark's optional exam review sessions frequently.

"In my limited interaction with Cody, I did not notice anything about him that made me think that he might later commit such a violent act," Clark said. "Otherwise, I would have reported my concern."

Andrew Matyasovski, a senior engineering major who lived next door to Cody Cousins, said the 23-year-old was a friendly neighbor, the last guy he would suspect of violence.

"He just seemed like a pretty normal college student," Matyasovski said. "I would have never imagined anything like this happening."

But Ashley Eidsmore, a graduate teaching assistant in the engineering school, told The Associated Press some of her lab mates who worked closely with Cody Cousins complained that he was a "just all-around rude individual."

Purdue Professor Thomas Talavage, who worked with Cody Cousins, said he was intense and aggressive about his projects.

"He didn't like to be told he was wrong," Talavage said. "He tended to be more aggressive in his debating and tended to be more convinced he was right."

Talavage noted that electrical engineering students are under tremendous pressure and many don't graduate from the program even though they were top students before coming to Purdue.

Cody Cousins' recently retained lawyer, Robert Gever of Fort Wayne, Ind., said he intended to provide his client with the best defense possible. He met with the Cousins family before the courtroom appearance.

"Our hearts and their hearts are full of compassion and concern for the Purdue family and the family of Mr. Boldt," Gever said.

Boldt's funeral will be Tuesday, a week after the shooting, at his family's church, St. Frances Cabrini Catholic Church, in West Bend.